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Tcl_ListObj(3)                             Tcl Library Procedures                             Tcl_ListObj(3)



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NAME
       Tcl_ListObjAppendList,  Tcl_ListObjAppendElement,  Tcl_NewListObj, Tcl_SetListObj, Tcl_ListObjGetEle-ments, Tcl_ListObjGetElements,
       ments, Tcl_ListObjLength, Tcl_ListObjIndex, Tcl_ListObjReplace - manipulate Tcl objects as lists

SYNOPSIS
       #include <tcl.h>

       int
       Tcl_ListObjAppendList(interp, listPtr, elemListPtr)

       int
       Tcl_ListObjAppendElement(interp, listPtr, objPtr)

       Tcl_Obj *
       Tcl_NewListObj(objc, objv)

       Tcl_SetListObj(objPtr, objc, objv)

       int
       Tcl_ListObjGetElements(interp, listPtr, objcPtr, objvPtr)

       int
       Tcl_ListObjLength(interp, listPtr, intPtr)

       int
       Tcl_ListObjIndex(interp, listPtr, index, objPtrPtr)

       int
       Tcl_ListObjReplace(interp, listPtr, first, count, objc, objv)

ARGUMENTS
       Tcl_Interp *interp (in)                   If an error occurs while converting an object to be a  list
                                                 object,  an  error  message  is  left  in the interpreter's
                                                 result object unless interp is NULL.

       Tcl_Obj *listPtr (in/out)                 Points to the list object to be  manipulated.   If  listPtr
                                                 does not already point to a list object, an attempt will be
                                                 made to convert it to one.

       Tcl_Obj *elemListPtr (in/out)             For Tcl_ListObjAppendList, this points  to  a  list  object
                                                 containing elements to be appended onto listPtr.  Each ele-ment element
                                                 ment of *elemListPtr will become a new element of  listPtr.
                                                 If *elemListPtr is not NULL and does not already point to a
                                                 list object, an attempt will be made to convert it to  one.

       Tcl_Obj *objPtr (in)                      For Tcl_ListObjAppendElement, points to the Tcl object that
                                                 will be appended  to  listPtr.   For  Tcl_SetListObj,  this
                                                 points  to  the Tcl object that will be converted to a list
                                                 object containing the objc elements of the array referenced
                                                 by objv.

       int *objcPtr (in)                         Points  to location where Tcl_ListObjGetElements stores the
                                                 number of element objects in listPtr.

       Tcl_Obj ***objvPtr (out)                  A location where Tcl_ListObjGetElements stores a pointer to
                                                 an array of pointers to the element objects of listPtr.

       int objc (in)                             The  number  of Tcl objects that Tcl_NewListObj will insert
                                                 into a new list object, and Tcl_ListObjReplace will  insert
                                                 into  listPtr.   For  Tcl_SetListObj,  the  number  of  Tcl
                                                 objects to insert into objPtr.

       Tcl_Obj *const objv[] (in)                An array  of  pointers  to  objects.   Tcl_NewListObj  will
                                                 insert these objects into a new list object and Tcl_ListOb-jReplace Tcl_ListObjReplace
                                                 jReplace will insert them into an existing  listPtr.   Each
                                                 object will become a separate list element.

       int *intPtr (out)                         Points  to  location  where  Tcl_ListObjLength  stores  the
                                                 length of the list.

       int index (in)                            Index of the  list  element  that  Tcl_ListObjIndex  is  to
                                                 return.  The first element has index 0.

       Tcl_Obj **objPtrPtr (out)                 Points  to  place  where  Tcl_ListObjIndex  is  to  store a
                                                 pointer to the resulting list element object.

       int first (in)                            Index of the starting list element that  Tcl_ListObjReplace
                                                 is to replace.  The list's first element has index 0.

       int count (in)                            The  number  of  elements  that  Tcl_ListObjReplace  is  to
                                                 replace.
____________________________________________________________________________________________________________


DESCRIPTION
       Tcl list objects have an internal representation that supports the efficient indexing and  appending.
       The  procedures  described in this man page are used to create, modify, index, and append to Tcl list
       objects from C code.

       Tcl_ListObjAppendList and Tcl_ListObjAppendElement both add one or more objects to  the  end  of  the
       list  object  referenced  by  listPtr.  Tcl_ListObjAppendList appends each element of the list object
       referenced by elemListPtr while Tcl_ListObjAppendElement appends  the  single  object  referenced  by
       objPtr.  Both procedures will convert the object referenced by listPtr to a list object if necessary.
       If an error occurs during conversion, both procedures return TCL_ERROR and leave an error message  in
       the  interpreter's  result  object if interp is not NULL.  Similarly, if elemListPtr does not already
       refer to a list object, Tcl_ListObjAppendList will attempt to convert it  to  one  and  if  an  error
       occurs  during  conversion,  will  return  TCL_ERROR  and leave an error message in the interpreter's
       result object if interp is not NULL.  Both procedures invalidate any  old  string  representation  of
       listPtr  and, if it was converted to a list object, free any old internal representation.  Similarly,
       Tcl_ListObjAppendList frees any old internal representation of elemListPtr if it  converts  it  to  a
       list  object.  After appending each element in elemListPtr, Tcl_ListObjAppendList increments the ele-ment's element's
       ment's reference count since listPtr now also refers to it.  For the same  reason,  Tcl_ListObjAppen-dElement Tcl_ListObjAppendElement
       dElement  increments  objPtr's reference count.  If no error occurs, the two procedures return TCL_OK
       after appending the objects.

       Tcl_NewListObj and Tcl_SetListObj create a new object or modify an existing object to hold  the  objc
       elements of the array referenced by objv where each element is a pointer to a Tcl object.  If objc is
       less than or equal to zero, they return an empty object.  The new object's string  representation  is
       left  invalid.   The  two procedures increment the reference counts of the elements in objc since the
       list object now refers to them.  The new list object returned by Tcl_NewListObj has  reference  count
       zero.

       Tcl_ListObjGetElements  returns  a  count and a pointer to an array of the elements in a list object.
       It returns the count by storing it in the address objcPtr.  Similarly, it returns the  array  pointer
       by  storing  it  in  the  address objvPtr.  The memory pointed to is managed by Tcl and should not be
       freed or written to by the caller. If the list is empty, 0 is stored at objcPtr and NULL at  objvPtr.
       If listPtr is not already a list object, Tcl_ListObjGetElements will attempt to convert it to one; if
       the conversion fails, it returns TCL_ERROR and leaves an error message in  the  interpreter's  result
       object if interp is not NULL.  Otherwise it returns TCL_OK after storing the count and array pointer.

       Tcl_ListObjLength returns the number of elements in  the  list  object  referenced  by  listPtr.   It
       returns  this count by storing an integer in the address intPtr.  If the object is not already a list
       object, Tcl_ListObjLength will attempt to convert it to one; if  the  conversion  fails,  it  returns
       TCL_ERROR and leaves an error message in the interpreter's result object if interp is not NULL.  Oth-erwise Otherwise
       erwise it returns TCL_OK after storing the list's length.

       The procedure Tcl_ListObjIndex returns a pointer to the object at element index in  the  list  refer-enced referenced
       enced  by  listPtr.   It returns this object by storing a pointer to it in the address objPtrPtr.  If
       listPtr does not already refer to a list object, Tcl_ListObjIndex will attempt to convert it to  one;
       if the conversion fails, it returns TCL_ERROR and leaves an error message in the interpreter's result
       object if interp is not NULL.  If the index is out of range, that is, index is  negative  or  greater
       than  or equal to the number of elements in the list, Tcl_ListObjIndex stores a NULL in objPtrPtr and
       returns TCL_OK.  Otherwise it returns TCL_OK after storing the element's object pointer.  The  refer-ence reference
       ence  count  for the list element is not incremented; the caller must do that if it needs to retain a
       pointer to the element.

       Tcl_ListObjReplace replaces zero or more elements of the list referenced by  listPtr  with  the  objc
       objects  in the array referenced by objv.  If listPtr does not point to a list object, Tcl_ListObjRe-place Tcl_ListObjReplace
       place will attempt to convert it to one; if the conversion fails, it returns TCL_ERROR and leaves  an
       error message in the interpreter's result object if interp is not NULL.  Otherwise, it returns TCL_OK
       after replacing the objects.  If objv is NULL, no new elements are added.  If the argument  first  is
       zero or negative, it refers to the first element.  If first is greater than or equal to the number of
       elements in the list, then no elements are deleted; the new elements are appended to the list.  count
       gives  the number of elements to replace.  If count is zero or negative then no elements are deleted;
       the new elements are simply inserted before the one designated by first.  Tcl_ListObjReplace  invali-dates invalidates
       dates  listPtr's  old string representation.  The reference counts of any elements inserted from objv
       are incremented since the resulting list now refers to them.  Similarly, the reference counts for any
       replaced objects are decremented.

       Because  Tcl_ListObjReplace combines both element insertion and deletion, it can be used to implement
       a number of list operations.  For example, the following code inserts the objc objects referenced  by
       the array of object pointers objv just before the element index of the list referenced by listPtr:

              result = Tcl_ListObjReplace(interp, listPtr, index, 0,
                      objc, objv);

       Similarly, the following code appends the objc objects referenced by the array objv to the end of the
       list listPtr:

              result = Tcl_ListObjLength(interp, listPtr, &length);
              if (result == TCL_OK) {
                  result = Tcl_ListObjReplace(interp, listPtr, length, 0,
                          objc, objv);
              }

       The count list elements starting at first can be deleted by simply calling Tcl_ListObjReplace with  a
       NULL objvPtr:

              result = Tcl_ListObjReplace(interp, listPtr, first, count,
                      0, NULL);

SEE ALSO
       Tcl_NewObj, Tcl_DecrRefCount, Tcl_IncrRefCount, Tcl_GetObjResult

KEYWORDS
       append,  index, insert, internal representation, length, list, list object, list type, object, object
       type, replace, string representation



Tcl                                                  8.0                                      Tcl_ListObj(3)